Energy conversion

8 units, with J as the base. Every value in the factor table is the number you multiply by, so reading across a row converts out of that unit and reading down a column converts into it.

Factor table

Energy conversion factors. Each cell is the value to multiply the row unit by to get the column unit.
from \ to	mJ	J	kJ	cal	kcal	eV	keV	MeV
mJ	1	0.001	1 × 10⁻⁶	2.39006 × 10⁻⁴	2.39006 × 10⁻⁷	6.24151 × 10¹⁵	6.24151 × 10¹²	6.24151 × 10⁹
J	1000	1	0.001	0.239006	2.39006 × 10⁻⁴	6.24151 × 10¹⁸	6.24151 × 10¹⁵	6.24151 × 10¹²
kJ	1 × 10⁶	1000	1	239.006	0.239006	6.24151 × 10²¹	6.24151 × 10¹⁸	6.24151 × 10¹⁵
cal	4184	4.184	0.004184	1	0.001	2.61145 × 10¹⁹	2.61145 × 10¹⁶	2.61145 × 10¹³
kcal	4.184 × 10⁶	4184	4.184	1000	1	2.61145 × 10²²	2.61145 × 10¹⁹	2.61145 × 10¹⁶
eV	1.60218 × 10⁻¹⁶	1.60218 × 10⁻¹⁹	1.60218 × 10⁻²²	3.82929 × 10⁻²⁰	3.82929 × 10⁻²³	1	0.001	1 × 10⁻⁶
keV	1.60218 × 10⁻¹³	1.60218 × 10⁻¹⁶	1.60218 × 10⁻¹⁹	3.82929 × 10⁻¹⁷	3.82929 × 10⁻²⁰	1000	1	0.001
MeV	1.60218 × 10⁻¹⁰	1.60218 × 10⁻¹³	1.60218 × 10⁻¹⁶	3.82929 × 10⁻¹⁴	3.82929 × 10⁻¹⁷	1 × 10⁶	1000	1

Prefixes such as milli, micro and kilo follow the SI prefixes table.

Common conversions

Joules to calories

1 J = 0.239006 cal. In reverse, 1 cal = 4.184 J.

Joules to calories
J	cal
1	0.239006
5	1.19503
10	2.39006
50	11.9503
100	23.9006
500	119.503

kcal to kJ

1 kcal = 4.184 kJ. In reverse, 1 kJ = 0.239006 kcal.

kcal to kJ
kcal	kJ
1	4.184
5	20.92
10	41.84
50	209.2
100	418.4
500	2092

eV to joules

1 eV = 1.60218 × 10⁻¹⁹ J. In reverse, 1 J = 6.24151 × 10¹⁸ eV.

eV to joules
eV	J
1	1.60218 × 10⁻¹⁹
5	8.01088 × 10⁻¹⁹
10	1.60218 × 10⁻¹⁸
50	8.01088 × 10⁻¹⁸
100	1.60218 × 10⁻¹⁷
500	8.01088 × 10⁻¹⁷

Worked example

1 J in cal
= 1 × 0.239006
= 0.239006 cal

Convert a number

The table gives the factor; the unit converter does the arithmetic, remembers the units you picked, and turns any conversion into a link you can share.